0XYGEN RADICALS AND IRON- AND ASBESTOS-INDUCED CANCER

本研究的长期目标是研究02的作用 自由基和铁在石棉诱发的癌症。 砷催化许多 与铁的反应相同，最致癌的形式可以 含铁量高达36%。 这一提议是基于这样一种假设： 铁会产生氧自由基， DNA导致石棉的生物效应。 铁催化 反应可产生H2 O2以经由内的芬顿反应产生.OH。 靶细胞和细胞外H2 O2，由活化的 巨噬细胞，可以增加靶细胞中的浓度，以刺激 芬顿反应和. OH的形成。具体目标是：1） 确定H2 O2添加对以下量的影响： 青石棉体外诱导的DNA损伤; 2）确定 加入细胞外H202对DNA的损伤量、细胞毒性 和青石棉处理的SHE细胞中的转化; 3）测定青石棉处理的SHE细胞中的 丁硫克百威亚砜亚胺的作用，一种抑制细胞增殖的化学物质， H2 O2的破坏，对DNA损伤量、细胞毒性和 在青石棉处理的SHE细胞中的转化，有或没有 4）确定细胞外H2 O2的铁消耗是否 青石棉影响SHE细胞中.OH和DNA碱基损伤的量 添加或不添加细胞外H2 O2;以及5）确定 自由基清除剂对DNA损伤量，细胞毒性， 和青石棉处理的SHE细胞中的转化， 加入细胞外H2 O2。 将研究两种类型的DNA损伤， DNA单链断裂（使用phi X174 RFI DNA体外或原位缺口 细胞中的翻译）和DNA碱基损伤（GC/MS-SIM）。 .OH的作用 将通过使用特定的自由基清除剂（水杨酸盐， DMSO，二甲基硫脲）。 细胞培养物中.OH的形成将 使用水杨酸盐定量。 丁硫氨磺酰亚胺将用于 确定细胞内H2 O2水平增加的影响。

The long term objective of this research is to investigate the role of 02 radicals and iron in asbestos-induced cancer. Asbestos catalyzes many of the same reactions that iron does and the most carcinogenic forms can contain as much as 36% iron. This proposal is based upon the hypothesis that iron is responsible for the generation of 02 radicals that damage DNA resulting in the biological effects of asbestos. Iron-catalyzed reactions may generate H202 to produce .OH via the Fenton reaction within the target cell, and extracellular H202, released by activated macrophages, may increase concentrations in the target cell to stimulate the Fenton reaction and formation of .OH. The specific aims are: 1) determine the effect of H202 addition on the quantity of crocidolite-induced DNA damage in vitro; 2) determine the effect of addition of extracellular H202 on the amount of DNA damage, cytotoxicity and transformation in crocidolite-treated SHE cells; 3) determine the effect of buthionine sulfoximine, a chemical that inhibits cellular destruction of H202, on the amount of DNA damage, cytotoxicity, and transformation in crocidolite-treated SHE cells with or without the addition of extracellular H202; 4) determine if iron-depletion of crocidolite affects the amount of .OH and DNA base damage in SHE cells with or without the addition of extracellular H202; and 5) determine the effect of radical scavengers on the amount of DNA damage, cytotoxicity, and transformation in crocidolite-treated SHE cells with or without the addition of extracellular H202. Two types of DNA damage will be studied, DNA single strand breaks (using phi X174 RFI DNA in vitro or in situ nick translation in cells) and DNA base damage (GC/MS-SIM). The role of .OH will be investigated by using specific radical scavengers (salicylate, DMSO, dimethylthiourea). The formation of .OH in cell cultures will be quantified using salicylate. Buthionine sulfoximine will be used to determine the effects of increased intracellular levels of H202.